Soda soap grease



Patented Dec. 5, 1939 UNITED STATES PATENT OFFICE SODA SOAP GREASE Vernon L. Ricketts, Martinez, Calil'., assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application February 1, 1937,

Serial No. 123,491

14 Claims.

the simple admixture of mineral oil to soda soaps,

thereby producing a lubricant which is suitable for use at high temperatures, and preventing or reducing leakage of the lubricant from the bearings at high temperatures. It is a further object of the invention to increase the yield of a grease of the type described in proportion to the soap content, while maintaining and often improving the stability of the grease at normal and at high temperatures. Still another object of the invention is to improve the stability of such a grease, as indicated by freedom from granulation, by absence of any tendency to bleed or separate either during manufacture or later in storage, and by resistance to breakdown from mechanical stirring or beating. Other objects will be apparent from the following specification.

In accordance with the present invention, these and other objects are achieved by incorporating into the grease a small quantity of a metal salt of an organic carboxylic acid containing an arcmatic ring. Salts of both light and heavy metals may be employed, but I prefer to employ salts of alkali metals or alkaline earth metals, particularly sodium. The negative radical of the salt may have the formula R.C(O) .0 where R represents an organic radical containing an aromatic ring which may or may not be substituted with hydrocarbon and/or non-hydrocarbon groups. The acid residue may be linked directly to the aromatic nucleus, or it may be linked thereto through an aliphatic or oxy-aliphatic chain, which may be saturated CnH2nor unsaturated .CnH2n2-, and which may be substituted with hydrocarbon and/or non-hydrocarbon groups.

The negative radical may, for example, contain one or more of the following substituents: Halogen, such as C1; amines, as NI-Iz, NHR or NRz (which R represents an aliphatic chain) aliphatic chains, such as CHa, CzHs; and hydroxyl, such as OH and ROH.- The radical R may, moreover, contain additional carbonyl-containing radicals, such as --C O OH, CHO, C(O) .ONH4 or -C(( .OM, wherein M represents a metal.

These salts apparently act as peptizing agents for the soda soap, and result in an effective dispersion of soap in oil, the formation of line lattices contributing to increased yields and improved stabilities. The salts are, moreover, preferably resistant to solution in oil, this property being of especial value in increasing the melting point of the grease.

Examples of suitable salts are: metal benzoate, CsHsC (O) .OM, metal cinnamate,

CsHsCI-I t CHC (O) .OM,

metal salicylate (HO) CsH4C(O) ,OM, metal xylate (CH3) 2C6H3C(0) .OM, and metal vanillate (CI-I30) (HO) CsI-IaC(O) .OM,

and their substituted homologues wherein M represents a metal, such as sodium, potassium, calcium, zinc, and aluminum, but preferably sodium.

The salt present in the composite grease, according to the present invention, is preferably present in concentrations between 0.1% and 6% by weight, although higher concentrations may also be employed. The salt may be formed apart from the step of saponification of the aliphatic material employed for the grease base, and added to the soap, either before or after admixture to mineral oil, and while the soap is heated; it may, however, also be formed in the same operation, as is explained below in the specific examples.

The soda soap may constitute between about 2.5% and 39% of the composite grease. The term soda soap, as used in the present specification and claims, designates sodium salts of carboxylic acids containing at least 10 carbon atoms, as, for examples, salts of higher fatty acids, of naphthenic acids, and of mineral oil sulfonates. While any of the commonly used saponiflable materials may be employed for the production of the soda soap, such as fats and fatty acids, it was found that best results are obtained by employing materials having aliphatic acid residues containing over 20 carbon atoms. Thus, the use of beeswax or degras is preferred over the use of such materials as spermaceti or palm oil. When saponifiable materials consist entirely or mainly of aliphatic acids or of esters of aliphatic acids of between 10 and 20 carbon atoms, it is desirable to add beeswax or degras or a similar material to the extent of at least 40% of the total saponiflables. The use of tallow, spermaceti or similar materials without the addition of materials containing higher aliphatic acids or acid residues often results in the production of a grease having a brittle texture, and may even cause granulation due to soap and oil separation.

The mineral oil constitutes between about 61% and 97.7% of the composite grease. A wide variety of viscous mineral oils may be employed for this purpose. For example, oils having viscosities between about 50 seconds and 250 seconds Say. Univ. at 210 F. may be used. Since, however, the greases, according to the present invention, generally have higher melting points, they must be compounded at elevated temperatures, as, for example, between 500 F. and 620 F., so that because of a fire hazard special precautions must be taken if oils of low flash points, such as those having viscosities less than 100 sec. Say. Univ. at 210 F. are employed. When oils having viscosities above 100 seconds are employed, no special precautions are generally necessary, but it is desirable to carry out the operation in an atmosphere of carbon dioxide or nitrogen when less viscous oils are used.

The grease may, for example, be prepared in the following manner: Approximately 0.5 to 1.0 volumes of the mineral oil and the calculated amount of 45 B. caustic soda are added to the melted saponifiables, the quantity of caustic soda depending upon the saponiilcation numbers of,

the fats, waxes, etc., for any specific formula, and also upon the percentage of the metal salt which is to be employed. The resulting mixture is heated while stirring to a temperature of approximately 250" F. to 325 F., for a period sufflcient to cause saponification, usually between thirty minutes to one hour. The material containing the negative radical of the metallic salt to be employed, such as, for example, benzoic acid, benzaldehyde, or ammonium benzoate, etc., is dissolved in a large body of the oil, and the resulting solution is then added slowly to the soap base while stirring. The balance of the mineral temperatures.

56 ploying the following ingredients:

oil is then added, and the product is heated to a high temperature, for example, 550 F. to 600 F., to destroy any seeds, granules of soap, salt, traces of caustic, etc., which might resist lower Rapid cooling in shallow following the heating is desirable to insure a smooth product.

The invention may be further understood from the following examples:

Example I Two greases, designated below as A and-B, were compounded in the manner described above em Per cent Per cent Beeswax l0. 0 l0. 0 7 acid 2. 0 0

Caustic soda (dry basis) '2. 0 l. 0 8. A. E. 60 motor oil or San Joaquin Valley 86. 0 89. 0

0 at 300 to 500 F. for 24 hours, or storage at 200 to 250 F. for '72 hours, or storage after heating for several months. The eiiect of the presence of the sodium benzoate is apparent from the following table, which compares the properties of the above greases produced under similar @0 61- tions, no sodium benzoate being present in zr'ease B:

Grease A Grease B Unworked penetration 127 00 Worked netration 221 202 Ubbeloh e melting point F.. Above 392 313 Apparent temperature at which product assumes mineral oil fluidity (approximate) F" 650 330 It will be noticed that there is a smaller difference between the worked and unworked penetrations for the grease A, and that this grease has a higher melting point and assumes mineral oil fluidity at considerably higher temperatures than grease B.

- Example I! Two greases, designated as C and D, were similarly compounded, employing degras instead of beeswax, the ingredients being as follows:

- Percent Percent Degras 10. 0 10. 0 Benzoic acid 2. 0 0 Caustic soda (dry basis) 2. 0 l. 3 S. A. E. 60 motor 01] ex San Joaquin Valley. 86.0 88. 7

The grease C was, similar in stability and appearance to the grease A; grease D was, however, slightlygranular and curdled. The properties of the two greases are given below:

Grease O Grease D Unworked penetration-. 104 321 Worked penetration 203 465 Ubbciohde melting point. F Above 392 252 Apparent temperature at which product assumes mineral oil fluidity (approximate) .F. 550 320 acids, hydrocinnamic, naphthoic, alkyl .naphthoic, naphthylacetic and similar monobasic acids, as well as aromatic polybasic acids, like phthalic acid. Moreover, it is not necessary to employ the acid, it being permissible to employ any compound capable of forming a salt with the alkali metal. Thus, ammonium salicylate may be used instead of salicylic acid, ammonia being evolved in the process. Similarly, benzaldehyde may be used for this reaction, sodium benzoate and benzyl alcohol being produced.

The grease compositions of the present invention are useful in solving a large number of lubrication problems in which the high melting points and superior stability of lubricants of the present invention contribute to reduced leakage, more eflicient lubrication, and reduced maintenance costs. A few examples of such applications are: transmission and difierential lubrication, particularly in automobiles, automotive chassis lubrication, universal joint lubrication, roller bearing lubrication, ball bearing lubrication, rocker arm lubrication, particularly in airplanes, journal lubrication in railway equipment, in lumber mills, and in other industrial plants.

The properties of the grease are further apparent from the following tests: 16 grams of grease A of Example I were charged into a ball bearing machine comprising an unloaded ball bearing mounted on a vertical spindle, and surrounded by a grease cup extending several centimeters above the plane of the bearing. The machine was operated for 20 minutes at 4600 R. P. M. without the application of external heat, the temperature rising spontaneously to about 150 F. No pronounced tendency for the lubricant to form fibers or work out of the bearing was noted. At the completion of the test the grease remained unchanged in appearance and structure. There was no evidence of breakdown or of separation of oil and soap.

A similar test was performed for 30 minutes, applying heat to a maximum temperature of 450 F. Similar results were obtained, save that between 240 and 400 F. streamers of grease made their appearance above the plane of the bearing; but adequate lubricant was retained in the bearing in spite of the high speed of operation. Above 400 F. the grease reacted quietly.

I claim as my invention:

1. A soda soap grease comprising a viscous mineral oil and a soda soap of an acid selected from the group consisting of higher fatty acids, naphthenic acids and mineral oil sulfonic acids, said grease containing a minor proportion of an alkali metal salt of an organic carboxylic acid Y containing an aromatic ring to prevent bleeding.

2. A soda soap grease comprising a viscous mineral oil and a soda soap of an acid selected from the group consisting of higher fatty acids, naphthenic acids and mineral oil sulfonic acids, said grease containing a minor proportion of sodium benzoate to prevent bleeding.

3. A soda soap grease comprising a viscous mineral oil and a soda soap of an acid selected from the group consisting of higher fatty acids, naphthenic acids and mineral oil sulfonic acids, said grease containing a minor proportion of sodium salicylate to prevent bleeding.

4. A soda soap grease comprising a viscous mineral oil and a soda soap of an acid selected from the group consisting of higher fatty acids, naphthenic acids and mineral oil sulfonic acids, said grease containing a minor proportion of sodium cinnamate to prevent bleeding.

5. A soda soap grease comprising between 61 and 97.7% of a viscous mineral oil and between 2.5 and 39% of a soda soap of an acid selected from the group consisting of higher fatty acids,

naphthenic acids and mineral oil sulphonic acid, said grease containing between .1 and 6% of an alkali metal salt of an organic carboxylic acid containing an aromatic ring to prevent bleeding.

6. A soda soap grease comprising between 61 and 97.7% of a viscous mineral oil and between 2.5.and 39% of a soda soap of an acid selected from the group consisting of higher fatty acids, naphthenic acids and mineral oil sulphonic acid, said grease containing between .1 and 6% of sodium benzoate to prevent bleeding.

7. A soda soap grease comprising between 61 and 97.7% of a viscous mineral oil and between 2.5 and 39% of a soda soap of an acid selected from the group consisting of higher fatty acids, naphthenic acids and mineral oil sulphonic acid, said grease containing between .1 and 6% of sodium salicylate to prevent bleeding.

8. A soda soap grease comprising between 61 and 97.7% of a viscous mineral oil and between 2.5 and 39% of a soda soap of an acid selected from the group consisting of higher fatty acids, naphthenic acids and mineral oil sulphonic acid, said grease containing between .1 and 6% of sodium cinnamate to prevent bleeding.

9. A soda soap grease comprising a viscous mineral oil and a soda soap of a higher fatty acid, said grease containing a minor proportion of an alkali metal salt of an organic carboxylic acid containing an aromatic ring to prevent bleeding.

10. The grease according to claim 9 in which the soda soap is derived from a saponifiable material selected from the class consisting of beeswax and degras. I

11. A soda soap grease comprising viscous mineral oil and a soda soap of an acid selected from a group consisting of higher fatty acids, naphthenic acids and mineral oil sulphonic acids, at least 40% of said soap consisting of a soda soap of saponifiable material of the type of beeswax, which is rich in fatty acids containing more than 20 carbon atoms, said grease containing a minor proportion of an alkali metal salt of an organic carboxyllc acid containing an aromatic ring to prevent bleeding.

12. The grease according to claim 11 in which the salt is sodium benzoate.

13. The grease according to claim 11 in which the salt is sodium salicylate.

14. The grease according to claim 11 in which the salt is sodium cinnamate. I

VERNON L. RICKE'ITS. 

